;;; cl-simple-example.lisp --- Common Lisp port of rocksdb/example/c_simple_example.c

 ;; ref: https://github.com/facebook/rocksdb/blob/main/examples/c_simple_example.c

 ;;; Usage: 

 ;; To compile and run from the shell:

 #|

 sbcl --eval '(ql:quickload :rdb)' \

      --eval '(ql:quickload :cli)' \

      --eval '(compile-file "cl-simple-example.lisp")' \

      --eval '(load "cl-simple-example.fasl")' \

      --eval "(sb-ext:save-lisp-and-die \"cl-simple-example\" :toplevel #'cl-simple-example::main :executable t)"

 time ./cl-simple-example

 |#

 ;; Compare to C:

 #|

 # in rocksdb/examples

 gcc -lrocksdb c_simple_example.c -oc_simple_example

 time ./c_simple_example

 |#

 ;;; Code:

 (defpackage :examples/rdb/cl-simple-example

   (:nicknames :cl-simple-example)

   (:use :cl :std :cli :rdb :sb-alien :rocksdb)

   (:export :main))

 (rocksdb:load-rocksdb :save t)

 (in-package :cl-simple-example)

 (in-readtable :std)

 (defvar *num-cpus* (alien-funcall (extern-alien "sysconf" (function long integer)) sb-unix:sc-nprocessors-onln)

   "CPU count.")

 (defparameter *db-path* "/tmp/rocksdb-cl-simple-example")

 (defparameter *db-backup-path* "/tmp/rocksdb-cl-simple-example-backup")

 (defmain ()

   ;; open Backup Engine that we will use for backing up our database

   (let ((options 

           (make-rocksdb-options 

                   (lambda (opt)

                     (rocksdb-options-increase-parallelism opt *num-cpus*) ;; set # of online cores

                     (rocksdb-options-optimize-level-style-compaction opt 0)

                     (rocksdb-options-set-create-if-missing opt 1)))))

   (with-open-backup-engine-raw (be *db-backup-path* options)

     ;; open DB

     (with-open-db-raw (db *db-path* options)

       ;; put key-value

       (put-kv-str-raw db "key" "value")

       ;; get value

       (string= (get-kv-str-raw db "key") "value")

       ;; create new backup in a directory specified by *db-backup-path*

       (create-new-backup-raw be db))

     ;; if something is wrong, you might want to restore data from last backup

     (restore-from-latest-backup-raw be *db-path* *db-backup-path*))))